That's possible as long as you're careful about which way you do it. Turn the crank AWAY from TDC, even if that's backwards. You don't want to move it through the position where #2 & 3 are TDC. Now all 4 pistons are mid-stroke. You can turn the cam any way you want.

Then move the crank directly to TDC, making sure you don't turn it thru the other's TDC position.